1. Field of the Invention
The present invention relates to an apparatus and a method for manufacturing magnetic head sliders, in particular, including surface treatment.
2. Related Art
A magnetic head slider used for a hard disk drive is required to fly at a low amplitude above a magnetic disk with high accuracy. To achieve that, an ABS ((Air Bearing Surface) flying surface) in a predetermined shape must be formed on the surface of the magnetic head facing the magnetic disk, and the surface must be treated by polishing (lapping) with high accuracy. At the same time, in polishing, the MR height (length of the Magnet-Resistive element from the ABS) of the magnetic head slider would be adjusted so as to read and write data on the magnetic disk. Since the reading and writing performance to the magnetic disk depend strongly on the MR height, highly accurate adjustment of the MR height is needed.
For those reasons, polishing the ABS is one of important steps while processing the magnetic head slider. Further, the surface opposite to the ABS (back surface) of the magnetic slider is to be attached onto a suspension constituting a Head Gimbal Assembly (HGA). Therefore, if the surface roughness of the back surface is big, the magnetic head slider cannot be attached onto the suspension with high accuracy, so the flying height above the magnetic disk and the flying posture angle may be affected. In addition, the back surface is also required to have parallelism with the ABS. This is because the parallelism between the surface to be mounted on the suspension and the ABS affects the flying posture angle of the magnetic head slider, so it causes the flying height of the magnetic head slider to fluctuate. Therefore, polishing the back surface of the ABS with highly accuracy is also required.
Conventional method of manufacturing magnetic head sliders including polishing the ABS and its back surface will be explained. In the method disclosed in the specification of the U.S. Pat. No. 5,406,694 (Patent Document 1), a wafer block, an array of the magnetic head sliders aligned in rows and columns, is cut out from a wafer on which magnetic head elements of a plurality of magnetic head sliders are formed. Then, while holding the both end sides of the wafer block with jigs, a bar block which is a row of the magnetic head slider in the wafer block is cut out from the wafer block. Then, an ABS of magnetic head slider formed on the cutting surface of the bar block is polished by a dedicated device. Then, pattern is formed on the ABS through steps of etching the ABS, the bar block would be cut into pieces of magnetic head sliders, whereby magnetic head sliders are manufactured.
Methods disclosed in the pamphlet of International Publication No. WO00/39801 (Patent Document 2), Japanese Patent Laid-Open Publication No. 9-7149 (Patent Document 3), and Japanese Patent Laid-Open Publication No. 8-315344 (Patent Document 4) adopt such methods that with respect to a bar block cut out from a wafer block in the same way as described above, both ABS and its back surface are sandwiched by grindstones and polished simultaneously, or the front and back surfaces are polished separately.
However, as hard disk drive has been shrunk in the size recently, the size of a magnetic head slider also has been further shrunk. Therefore, in the manufacturing process, handling such as fixing a member in a bar-block shape to a jig and polishing it is getting more difficult. In particular, direct handling of the minute and elongated fragile bar block would induce considerable damage to the magnetic head slider.
In view of the above, as shown in Japanese Patent Laid-open Publication No. 11-316928 (Patent Document 5) and Japanese Patent Laid-open Publication No. 11-328642 (Patent Document 6), methods including polishing ABS before cutting into a bar block have been disclosed. More specifically, in the method disclosed in Patent Document 5, first of all, wafer block in which magnetic head sliders are arranged in a plurality of rows of bar blocks is cut out, and is mounted on a support plate. Next, ABS of magnetic head sliders positioned at the end thereof is polished. Then, a tape is used so as to cover the polished ABS, and the bar block is cut out from the wafer block in such a state. Then, the bar block is held with vacuum tweezer and mounted on a jig for polishing the back surface, and the back surface is polished. The method disclosed in Patent Document 6 is same as that described above. First of all, ABS is polished in a wafer block state, and a bar block is cut out. After that, the bar block is adhered to a work holder with the ABS being the adhered surface, and the back surface is polished.
The above-described methods will be explained briefly with reference to FIGS. 12A to 12D. First of all, as shown in FIG. 12A, a wafer block 110 is held by a holding jig 101, and a bar block 111 positioned at the end face is cut out by a cutting grindstone 131 provided to a cutting device 103 (FIG. 12B). Note that the ABS which is an end face 111a of the cut-out bar block 111 has been polished previously in the step shown in FIG. 12D described later. Then, to the cut-out bar block 111, the back surface which is the cut surface 111b is polished by a polishing grindstone 132 as shown in FIG. 12C. On the other hand, to the remaining wafer block, the ABS 111a of the next bar block positioned at the cut surface is polished by a polishing grindstone 133 as shown FIG. 12D, and then cutting process of FIG. 12A is repeated.
[Patent Document 1] U.S. Pat. No. 5,406,694
[Patent Document 2] WO00/39801
[Patent Document 3] JP9-7149A
[Patent Document 4] JP8-315344A
[Patent Document 5] JP11-316928A
[Patent Document 6] JP11-328642A
However, the conventional examples described above involve the following disadvantages. In the art, because polishing of ABS or back surface is performed after cutting into a bar blocks it is still necessary to handle the elongated fragile bar block directly. It may cause the damage of magnetic head sliders. In addition, considerable process such as mounting of the minute fragile bar block on a predetermined jig is necessary. In other words, in manufacturing magnetic head sliders which needs high process quality, it may cause problems of complication and delay of the manufacturing process, leading to the product quality's deteriorating easily.